• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.160-165
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• 2004

At this research, we examined probability of light bulb's life span value and prediction on purpose to inquire out the span of repeat velocity as fracture probability by executing the fatigue test, which is considered property of Tungsten filament's thermal fatigue used as an automobile bulb. As a result we can confirm what the most suitable solution is weibull distribution and log normal distribution. Tungsten filament's span gets longer as the fatigue repeat velocity gets shorter And, repeat span is about 15%~40% shorter than sequence life span.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.519-524
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• 1999

A bulb-tee sectioned girder is proposed for long span bridge exceeding 40 meters. The proposed bulb-tee girder is developed by non-linear analysis process. This study investigates the structural behavior and efficiency of proposed bulb-tee sectioned girder using 1/2 scaled prototype beam specimen. Three specimens are tested under three point static loading system. The crack patterns, failure mode and ultimate load capacity of each specimen are reported in this paper and they are compared to each other.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1261-1267
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• 2007

Although LEDs have been used in various applications with improving the brightness and luminous efficacy, the electrical and optical characteristics of high power LED varies at different temperature and starting time. In this paper, optimal heat sink and apparatus design were conducted using IR camera and ICEPAK on the LED bulb consisting with fourteen LED array. The temperatures of heat sink and LED device of the designed LED bulb without cooling pan were $74^{\circ}C\;and\;96.8^{\circ}C$, respectively, showing in good themal characteristics. For high efficiency driving circuit of LED array adopted optimal heat sink design, driving circuits of constant voltage and current circuits were suggested and fabricated. As a result the efficacy of all driving circuits showed more than 20 lm/W. Also, the constant current circuits are suitable for signal lamp, hallway lamp, and flash lamp having short operating time(about 30 min). On the other hand, a reading light and indoor lamp having long operating time can be controlled by constant voltage circuit.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.418-425
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• 2009

A vertical bulb turbine unit with elbow type draft tube has been developed due to avoidance of complicated assembling and long standstill period at overhaul in comparison with conventional horizontal bulb turbine unit. Before designing the prototype vertical bulb unit, a hydrographic model test was carried out to establish the ideal design concept for this innovative generating unit. Froude similarity is not available for vortex occurrence. Consequently, an intake structure without air entraining vortices under all the flow conditions is developed, and it is confirmed that the surge wave at load rejection is not affected harmful influence for other constructions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.9
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• pp.779-785
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• 2003

The present work proposed a newly developed fluidized bed-type psychrometer that could be applicable to the high temperature and contaminant gases. The psychrometer is a device that test gas passes through the water in a glass bottle as a bubbly flow to obtain the adiabatic saturation temperature. A fluidized bed-type psychrometer was made and its characteristics were compared with the Assmann Psychrometer. The characteristic time was in the order of a hundred seconds, and decreased for the decrease of the mass of water and the increase of the air flow rate. The air flow rate and the insulation of the glass bottle were definitely important in the accurate measurement of the wet bulb temperature. The error in wet bulb temperature became less than 5 percent of the difference of dry and wet bulb temperatures if the air velocity in the glass bottle was greater than 1.5m/s.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.23 no.2
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• pp.141-144
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• 1978

To obtain information on the status of vegetative and reproductive growth of Fritillariae rhizoma-bulb were sown in 5 levels-weight (1. 5 gram, 3gram. .5gram, 7gram, and 9gram). Results observed were as follows; A clear plus correlations were shown between the germination status, plant height and other agronomic characteristics and the weight of rhizoma-bulb. As the weight of rhizoma-bulb was increasing, also the number of flower and yields were increased.

• International Journal of Fluid Machinery and Systems
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• v.4 no.1
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• pp.140-149
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• 2011

For a certain operating point of a horizontal shaft bulb turbine (i.e. volume flow, net head, blade angle, guide vane angle) the efficiency for different pressure levels (i.e. different Thoma-coefficient ${\sigma}$) is calculated using a commercial Computational Fluid Dynamics (CFD-)-code including two-phase flow and a cavitation model. The results are compared with experimental results achieved at a closed loop test rig for model turbines. The comparison of the experimentally and numerically obtained efficiency and the visual impression of the cavitation show a good agreement. Especially the drop in efficiency is calculated with satisfying accuracy. This drop in efficiency in combination with the visual impression is of high practical importance since it contributes to determine the admissible cavitation in a bulb-turbine. It is seen that the incipient cavitation in Kaplan type turbines has no major importance in determing this admissible amount of cavitation.

• Solar Energy
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• v.19 no.1
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• pp.59-65
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• 1999

The zone of greenhouse in Korea increase on a scale yearly. Particularly, greenhouse take up a important value on the agriculture economy. Greenhouse of scale, material, heating system, and drain is progressing to industrialization. The dry bulb temperature, humidity, photosynthesis and so forth are necessary to maintain environment control of greenhouse. The dry bulb temperature among them greatly affects growing of a plant. The purpose of this study is to analyzed the indoor environment control system and the characteristic of dry bulb temperature distribution on a large scale greenhouse in summer season.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.04b
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• pp.51-56
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• 2001

This study was carried out to research the effect of nutrient composition and GA4＋7 on growth, flower quality and bulb development in special hydroponics of cut tulip. Flowering of 'Cassini' was markedly accelerated by standard+GA4＋7, K200＋GA4＋7, N250＋GA4＋7 treatment, last internode was increased by N250 as compared with other treatment. For 'Christmas Marvel', flowering was promoted by K250＋GA4＋7, last infernode and total length were also increased with K250＋GA4＋7 as compared to other treatment. For 'Golden Apeldoorn', flowering was accelerated by K200＋GA4＋7, last internode was increased with N300＋GA4＋7 treatment and total length was increased in N250＋GA4＋7 treatment as compared with the standard plants. Bulb weight and number of 'Cassini', 'Christmas Marvel'and 'Golden Apeldoorn' were decreased by GA4＋7 as compared to non-treatment, and bulb diameter was not affected by GA4＋7.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.585-590
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• 2001

Bulbs of Lilium Oriental hybrids cv. 'Casablanca' and 'Marco Polo' were grown in a plastic house in alpine area of Pyongchang Kangwondo. Saw-dust, black film, reflective film, transparent film, and white/black double film were used as mulching materials to ascertain the growth of foliage, the quality of flower, and the size of bulbs. Foliage weights of both lilies were higher when lilies were grown with mulching materials than control. There were no differences of bulb weight among the control and mulching treatments, except delayed bulb growth in black film and white/black double film. Mulching cultivation with saw-dust and reflective film stimulated foliage growth, root growth and bulb production, but black film delayed the growth and development. Transparent and white/black double films showed no effects on foliage growth and bulb development than the control. As mulching materials tended to delay lily growth, including foliage and bulb, an extension of growing term might be better to produce high quality lilies than common cultivation in alpine area.